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postgresql/src/backend/catalog/heap.c

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/*-------------------------------------------------------------------------
*
* heap.c
* code to create and destroy POSTGRES heap relations
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.204 2002/06/20 20:29:26 momjian Exp $
*
*
* INTERFACE ROUTINES
* heap_create() - Create an uncataloged heap relation
* heap_create_with_catalog() - Create a cataloged relation
* heap_drop_with_catalog() - Removes named relation from catalogs
*
* NOTES
* this code taken from access/heap/create.c, which contains
* the old heap_create_with_catalog, amcreate, and amdestroy.
* those routines will soon call these routines using the function
* manager,
* just like the poorly named "NewXXX" routines do. The
* "New" routines are all going to die soon, once and for all!
* -cim 1/13/91
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "access/genam.h"
#include "catalog/catalog.h"
#include "catalog/catname.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_relcheck.h"
#include "catalog/pg_statistic.h"
#include "catalog/pg_type.h"
#include "commands/comment.h"
#include "commands/trigger.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/planmain.h"
#include "optimizer/prep.h"
#include "optimizer/var.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "rewrite/rewriteRemove.h"
#include "storage/smgr.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/relcache.h"
#include "utils/syscache.h"
static void AddNewRelationTuple(Relation pg_class_desc,
Relation new_rel_desc,
Oid new_rel_oid, Oid new_type_oid,
char relkind, bool relhasoids);
static void DeleteAttributeTuples(Relation rel);
static void DeleteRelationTuple(Relation rel);
static void DeleteTypeTuple(Relation rel);
static void RelationRemoveIndexes(Relation relation);
static void RelationRemoveInheritance(Relation relation);
static void AddNewRelationType(const char *typeName,
Oid typeNamespace,
Oid new_rel_oid,
Oid new_type_oid);
static void StoreAttrDefault(Relation rel, AttrNumber attnum, char *adbin);
static void StoreRelCheck(Relation rel, char *ccname, char *ccbin);
static void StoreConstraints(Relation rel, TupleDesc tupdesc);
static void SetRelationNumChecks(Relation rel, int numchecks);
static void RemoveConstraints(Relation rel);
static void RemoveStatistics(Relation rel);
/* ----------------------------------------------------------------
* XXX UGLY HARD CODED BADNESS FOLLOWS XXX
*
* these should all be moved to someplace in the lib/catalog
* module, if not obliterated first.
* ----------------------------------------------------------------
*/
/*
* Note:
* Should the system special case these attributes in the future?
* Advantage: consume much less space in the ATTRIBUTE relation.
* Disadvantage: special cases will be all over the place.
*/
static FormData_pg_attribute a1 = {
0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
SelfItemPointerAttributeNumber, 0, -1, -1,
false, 'p', false, 'i', false, false
};
static FormData_pg_attribute a2 = {
0, {"oid"}, OIDOID, 0, sizeof(Oid),
ObjectIdAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
static FormData_pg_attribute a3 = {
0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
MinTransactionIdAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
static FormData_pg_attribute a4 = {
0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
MinCommandIdAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
static FormData_pg_attribute a5 = {
0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
MaxTransactionIdAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
static FormData_pg_attribute a6 = {
0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
MaxCommandIdAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
/*
* We decided to call this attribute "tableoid" rather than say
* "classoid" on the basis that in the future there may be more than one
* table of a particular class/type. In any case table is still the word
* used in SQL.
*/
static FormData_pg_attribute a7 = {
0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
TableOidAttributeNumber, 0, -1, -1,
true, 'p', false, 'i', false, false
};
static Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
/*
* This function returns a Form_pg_attribute pointer for a system attribute.
* Note that we elog if the presented attno is invalid.
*/
Form_pg_attribute
SystemAttributeDefinition(AttrNumber attno, bool relhasoids)
{
if (attno >= 0 || attno < -(int) lengthof(SysAtt))
elog(ERROR, "SystemAttributeDefinition: invalid attribute number %d",
attno);
if (attno == ObjectIdAttributeNumber && !relhasoids)
elog(ERROR, "SystemAttributeDefinition: invalid attribute number %d",
attno);
return SysAtt[-attno - 1];
}
/*
* If the given name is a system attribute name, return a Form_pg_attribute
* pointer for a prototype definition. If not, return NULL.
*/
Form_pg_attribute
SystemAttributeByName(const char *attname, bool relhasoids)
{
int j;
for (j = 0; j < (int) lengthof(SysAtt); j++)
{
Form_pg_attribute att = SysAtt[j];
if (relhasoids || att->attnum != ObjectIdAttributeNumber)
{
if (strcmp(NameStr(att->attname), attname) == 0)
return att;
}
}
return NULL;
}
/* ----------------------------------------------------------------
* XXX END OF UGLY HARD CODED BADNESS XXX
* ---------------------------------------------------------------- */
/* ----------------------------------------------------------------
* heap_create - Create an uncataloged heap relation
*
* rel->rd_rel is initialized by RelationBuildLocalRelation,
* and is mostly zeroes at return.
*
* Remove the system relation specific code to elsewhere eventually.
*
* If storage_create is TRUE then heap_storage_create is called here,
* else caller must call heap_storage_create later.
* ----------------------------------------------------------------
*/
Relation
heap_create(const char *relname,
Oid relnamespace,
TupleDesc tupDesc,
bool shared_relation,
bool storage_create,
bool allow_system_table_mods)
{
Oid relid;
Oid dbid = shared_relation ? InvalidOid : MyDatabaseId;
bool nailme = false;
RelFileNode rnode;
Relation rel;
/*
* sanity checks
*/
if (!allow_system_table_mods &&
(IsSystemNamespace(relnamespace) || IsToastNamespace(relnamespace)) &&
IsNormalProcessingMode())
elog(ERROR, "cannot create %s.%s: "
"system catalog modifications are currently disallowed",
get_namespace_name(relnamespace), relname);
/*
* Real ugly stuff to assign the proper relid in the relation
* descriptor follows. Note that only "bootstrapped" relations whose
* OIDs are hard-coded in pg_class.h should be listed here. We also
* have to recognize those rels that must be nailed in cache.
*/
if (IsSystemNamespace(relnamespace))
{
if (strcmp(TypeRelationName, relname) == 0)
{
nailme = true;
relid = RelOid_pg_type;
}
else if (strcmp(AttributeRelationName, relname) == 0)
{
nailme = true;
relid = RelOid_pg_attribute;
}
else if (strcmp(ProcedureRelationName, relname) == 0)
{
nailme = true;
relid = RelOid_pg_proc;
}
else if (strcmp(RelationRelationName, relname) == 0)
{
nailme = true;
relid = RelOid_pg_class;
}
else if (strcmp(ShadowRelationName, relname) == 0)
{
relid = RelOid_pg_shadow;
}
else if (strcmp(GroupRelationName, relname) == 0)
{
relid = RelOid_pg_group;
}
else if (strcmp(DatabaseRelationName, relname) == 0)
{
relid = RelOid_pg_database;
}
else
{
relid = newoid();
}
}
else
relid = newoid();
/*
* For now, the physical identifier of the relation is the same as the
* logical identifier.
*/
rnode.tblNode = dbid;
rnode.relNode = relid;
/*
* build the relcache entry.
*/
rel = RelationBuildLocalRelation(relname,
relnamespace,
tupDesc,
relid, dbid,
rnode,
nailme);
/*
* have the storage manager create the relation.
*/
if (storage_create)
heap_storage_create(rel);
return rel;
}
void
heap_storage_create(Relation rel)
{
Assert(rel->rd_fd < 0);
rel->rd_fd = smgrcreate(DEFAULT_SMGR, rel);
Assert(rel->rd_fd >= 0);
}
/* ----------------------------------------------------------------
* heap_create_with_catalog - Create a cataloged relation
*
* this is done in 6 steps:
*
* 1) CheckAttributeNames() is used to make certain the tuple
* descriptor contains a valid set of attribute names
*
* 2) pg_class is opened and get_relname_relid()
* performs a scan to ensure that no relation with the
* same name already exists.
*
* 3) heap_create() is called to create the new relation on disk.
*
* 4) AddNewRelationTuple() is called to register the
* relation in pg_class.
*
* 5) TypeCreate() is called to define a new type corresponding
* to the new relation.
*
* 6) AddNewAttributeTuples() is called to register the
* new relation's schema in pg_attribute.
*
* 7) StoreConstraints is called () - vadim 08/22/97
*
* 8) the relations are closed and the new relation's oid
* is returned.
*
* ----------------------------------------------------------------
*/
/* --------------------------------
* CheckAttributeNames
*
* this is used to make certain the tuple descriptor contains a
* valid set of attribute names. a problem simply generates
* elog(ERROR) which aborts the current transaction.
* --------------------------------
*/
static void
CheckAttributeNames(TupleDesc tupdesc, bool relhasoids, char relkind)
{
int i;
int j;
int natts = tupdesc->natts;
/*
* first check for collision with system attribute names
*
* Skip this for a view, since it doesn't have system attributes.
*/
if (relkind != RELKIND_VIEW)
{
for (i = 0; i < natts; i++)
{
if (SystemAttributeByName(NameStr(tupdesc->attrs[i]->attname),
relhasoids) != NULL)
elog(ERROR, "name of column \"%s\" conflicts with an existing system column",
NameStr(tupdesc->attrs[i]->attname));
}
}
/*
* also, warn user if attribute to be created has an unknown typid
* (usually as a result of a 'retrieve into' - jolly
*/
for (i = 0; i < natts; i++)
{
if (tupdesc->attrs[i]->atttypid == UNKNOWNOID)
elog(WARNING, "Attribute '%s' has an unknown type"
"\n\tProceeding with relation creation anyway",
NameStr(tupdesc->attrs[i]->attname));
}
/*
* next check for repeated attribute names
*/
for (i = 1; i < natts; i++)
{
for (j = 0; j < i; j++)
{
if (strcmp(NameStr(tupdesc->attrs[j]->attname),
NameStr(tupdesc->attrs[i]->attname)) == 0)
elog(ERROR, "column name \"%s\" is duplicated",
NameStr(tupdesc->attrs[j]->attname));
}
}
}
/* --------------------------------
* AddNewAttributeTuples
*
* this registers the new relation's schema by adding
* tuples to pg_attribute.
* --------------------------------
*/
static void
AddNewAttributeTuples(Oid new_rel_oid,
TupleDesc tupdesc,
bool relhasoids,
char relkind)
{
Form_pg_attribute *dpp;
int i;
HeapTuple tup;
Relation rel;
bool hasindex;
Relation idescs[Num_pg_attr_indices];
int natts = tupdesc->natts;
/*
* open pg_attribute
*/
rel = heap_openr(AttributeRelationName, RowExclusiveLock);
/*
* Check if we have any indices defined on pg_attribute.
*/
hasindex = RelationGetForm(rel)->relhasindex;
if (hasindex)
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices, idescs);
/*
* first we add the user attributes..
*/
dpp = tupdesc->attrs;
for (i = 0; i < natts; i++)
{
/* Fill in the correct relation OID */
(*dpp)->attrelid = new_rel_oid;
/* Make sure these are OK, too */
(*dpp)->attstattarget = DEFAULT_ATTSTATTARGET;
(*dpp)->attcacheoff = -1;
tup = heap_addheader(Natts_pg_attribute,
ATTRIBUTE_TUPLE_SIZE,
(void *) *dpp);
simple_heap_insert(rel, tup);
if (hasindex)
CatalogIndexInsert(idescs, Num_pg_attr_indices, rel, tup);
heap_freetuple(tup);
dpp++;
}
/*
* next we add the system attributes. Skip OID if rel has no OIDs.
*/
if (relkind != RELKIND_VIEW)
{
dpp = SysAtt;
for (i = 0; i < -1 - FirstLowInvalidHeapAttributeNumber; i++)
{
if (relhasoids || (*dpp)->attnum != ObjectIdAttributeNumber)
{
Form_pg_attribute attStruct;
tup = heap_addheader(Natts_pg_attribute,
ATTRIBUTE_TUPLE_SIZE,
(void *) *dpp);
/* Fill in the correct relation OID in the copied tuple */
attStruct = (Form_pg_attribute) GETSTRUCT(tup);
attStruct->attrelid = new_rel_oid;
/*
* Unneeded since they should be OK in the constant data
* anyway
*/
/* attStruct->attstattarget = 0; */
/* attStruct->attcacheoff = -1; */
simple_heap_insert(rel, tup);
if (hasindex)
CatalogIndexInsert(idescs, Num_pg_attr_indices, rel, tup);
heap_freetuple(tup);
}
dpp++;
}
}
/*
* close pg_attribute indices
*/
if (hasindex)
CatalogCloseIndices(Num_pg_attr_indices, idescs);
heap_close(rel, RowExclusiveLock);
}
/* --------------------------------
* AddNewRelationTuple
*
* this registers the new relation in the catalogs by
* adding a tuple to pg_class.
* --------------------------------
*/
static void
AddNewRelationTuple(Relation pg_class_desc,
Relation new_rel_desc,
Oid new_rel_oid,
Oid new_type_oid,
char relkind,
bool relhasoids)
{
Form_pg_class new_rel_reltup;
HeapTuple tup;
Relation idescs[Num_pg_class_indices];
/*
* first we update some of the information in our uncataloged
* relation's relation descriptor.
*/
new_rel_reltup = new_rel_desc->rd_rel;
/*
* Here we insert bogus estimates of the size of the new relation. In
* reality, of course, the new relation has 0 tuples and pages, and if
* we were tracking these statistics accurately then we'd set the
* fields that way. But at present the stats will be updated only by
* VACUUM or CREATE INDEX, and the user might insert a lot of tuples
* before he gets around to doing either of those. So, instead of
* saying the relation is empty, we insert guesstimates. The point is
* to keep the optimizer from making really stupid choices on
* never-yet-vacuumed tables; so the estimates need only be large
* enough to discourage the optimizer from using nested-loop plans.
* With this hack, nested-loop plans will be preferred only after the
* table has been proven to be small by VACUUM or CREATE INDEX.
* Maintaining the stats on-the-fly would solve the problem more
* cleanly, but the overhead of that would likely cost more than it'd
* save. (NOTE: CREATE INDEX inserts the same bogus estimates if it
* finds the relation has 0 rows and pages. See index.c.)
*/
switch (relkind)
{
case RELKIND_RELATION:
case RELKIND_INDEX:
case RELKIND_TOASTVALUE:
new_rel_reltup->relpages = 10; /* bogus estimates */
new_rel_reltup->reltuples = 1000;
break;
case RELKIND_SEQUENCE:
new_rel_reltup->relpages = 1;
new_rel_reltup->reltuples = 1;
break;
default: /* views, etc */
new_rel_reltup->relpages = 0;
new_rel_reltup->reltuples = 0;
break;
}
new_rel_reltup->relowner = GetUserId();
new_rel_reltup->reltype = new_type_oid;
new_rel_reltup->relkind = relkind;
new_rel_reltup->relhasoids = relhasoids;
/* ----------------
* now form a tuple to add to pg_class
* XXX Natts_pg_class_fixed is a hack - see pg_class.h
* ----------------
*/
tup = heap_addheader(Natts_pg_class_fixed,
CLASS_TUPLE_SIZE,
(void *) new_rel_reltup);
/* force tuple to have the desired OID */
tup->t_data->t_oid = new_rel_oid;
/*
* finally insert the new tuple and free it.
*/
simple_heap_insert(pg_class_desc, tup);
if (!IsIgnoringSystemIndexes())
{
/*
* First, open the catalog indices and insert index tuples for the
* new relation.
*/
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_class_indices, pg_class_desc, tup);
CatalogCloseIndices(Num_pg_class_indices, idescs);
}
heap_freetuple(tup);
}
/* --------------------------------
* AddNewRelationType -
*
* define a complex type corresponding to the new relation
* --------------------------------
*/
static void
AddNewRelationType(const char *typeName,
Oid typeNamespace,
Oid new_rel_oid,
Oid new_type_oid)
{
/*
* The sizes are set to oid size because it makes implementing sets
* MUCH easier, and no one (we hope) uses these fields to figure out
* how much space to allocate for the type. An oid is the type used
* for a set definition. When a user requests a set, what they
* actually get is the oid of a tuple in the pg_proc catalog, so the
* size of the "set" is the size of an oid. Similarly, byval being
* true makes sets much easier, and it isn't used by anything else.
*/
TypeCreate(typeName, /* type name */
typeNamespace, /* type namespace */
new_type_oid, /* preassigned oid for type */
new_rel_oid, /* relation oid */
sizeof(Oid), /* internal size */
-1, /* external size */
'c', /* type-type (complex) */
',', /* default array delimiter */
F_OIDIN, /* input procedure */
F_OIDOUT, /* output procedure */
F_OIDIN, /* receive procedure */
F_OIDOUT, /* send procedure */
InvalidOid, /* array element type - irrelevant */
InvalidOid, /* domain base type - irrelevant */
NULL, /* default type value - none */
NULL, /* default type binary representation */
true, /* passed by value */
'i', /* default alignment - same as for OID */
'p', /* Not TOASTable */
-1, /* typmod */
0, /* array dimensions for typBaseType */
false); /* Type NOT NULL */
}
/* --------------------------------
* heap_create_with_catalog
*
* creates a new cataloged relation. see comments above.
* --------------------------------
*/
Oid
heap_create_with_catalog(const char *relname,
Oid relnamespace,
TupleDesc tupdesc,
char relkind,
bool shared_relation,
bool relhasoids,
bool allow_system_table_mods)
{
Relation pg_class_desc;
Relation new_rel_desc;
Oid new_rel_oid;
Oid new_type_oid;
/*
* sanity checks
*/
Assert(IsNormalProcessingMode() || IsBootstrapProcessingMode());
if (tupdesc->natts <= 0 || tupdesc->natts > MaxHeapAttributeNumber)
elog(ERROR, "Number of columns is out of range (1 to %d)",
MaxHeapAttributeNumber);
CheckAttributeNames(tupdesc, relhasoids, relkind);
if (get_relname_relid(relname, relnamespace))
elog(ERROR, "Relation '%s' already exists", relname);
/*
* Tell heap_create not to create a physical file; we'll do that below
* after all our catalog updates are done. (This isn't really
* necessary anymore, but we may as well avoid the cycles of creating
* and deleting the file in case we fail.)
*/
new_rel_desc = heap_create(relname,
relnamespace,
tupdesc,
shared_relation,
false,
allow_system_table_mods);
/* Fetch the relation OID assigned by heap_create */
new_rel_oid = new_rel_desc->rd_att->attrs[0]->attrelid;
/* Assign an OID for the relation's tuple type */
new_type_oid = newoid();
/*
* now create an entry in pg_class for the relation.
*
* NOTE: we could get a unique-index failure here, in case someone else
* is creating the same relation name in parallel but hadn't committed
* yet when we checked for a duplicate name above.
*/
pg_class_desc = heap_openr(RelationRelationName, RowExclusiveLock);
AddNewRelationTuple(pg_class_desc,
new_rel_desc,
new_rel_oid,
new_type_oid,
relkind,
relhasoids);
/*
* since defining a relation also defines a complex type, we add a new
* system type corresponding to the new relation.
*
* NOTE: we could get a unique-index failure here, in case the same name
* has already been used for a type.
*/
AddNewRelationType(relname, relnamespace, new_rel_oid, new_type_oid);
/*
* now add tuples to pg_attribute for the attributes in our new
* relation.
*/
AddNewAttributeTuples(new_rel_oid, new_rel_desc->rd_att,
relhasoids, relkind);
/*
* store constraints and defaults passed in the tupdesc, if any.
*
* NB: this may do a CommandCounterIncrement and rebuild the relcache
* entry, so the relation must be valid and self-consistent at this point.
* In particular, there are not yet constraints and defaults anywhere.
*/
StoreConstraints(new_rel_desc, tupdesc);
/*
* We create the disk file for this relation here
*/
if (relkind != RELKIND_VIEW)
heap_storage_create(new_rel_desc);
/*
* ok, the relation has been cataloged, so close our relations and
* return the oid of the newly created relation.
*/
heap_close(new_rel_desc, NoLock); /* do not unlock till end of xact */
heap_close(pg_class_desc, RowExclusiveLock);
return new_rel_oid;
}
/* --------------------------------
* RelationRemoveInheritance
*
* Note: for now, we cause an exception if relation is a
* superclass. Someday, we may want to allow this and merge
* the type info into subclass procedures.... this seems like
* lots of work.
* --------------------------------
*/
static void
RelationRemoveInheritance(Relation relation)
{
Relation catalogRelation;
HeapTuple tuple;
HeapScanDesc scan;
ScanKeyData entry;
bool found = false;
/*
* open pg_inherits
*/
catalogRelation = heap_openr(InheritsRelationName, RowExclusiveLock);
/*
* form a scan key for the subclasses of this class and begin scanning
*/
ScanKeyEntryInitialize(&entry, 0x0, Anum_pg_inherits_inhparent,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(relation)));
scan = heap_beginscan(catalogRelation,
SnapshotNow,
1,
&entry);
/*
* if any subclasses exist, then we disallow the deletion.
*/
if ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
Oid subclass = ((Form_pg_inherits) GETSTRUCT(tuple))->inhrelid;
char *subclassname;
subclassname = get_rel_name(subclass);
/* Just in case get_rel_name fails... */
if (subclassname)
elog(ERROR, "Relation \"%s\" inherits from \"%s\"",
subclassname, RelationGetRelationName(relation));
else
elog(ERROR, "Relation %u inherits from \"%s\"",
subclass, RelationGetRelationName(relation));
}
heap_endscan(scan);
/*
* If we get here, it means the relation has no subclasses so we can
* trash it. First we remove dead INHERITS tuples.
*/
entry.sk_attno = Anum_pg_inherits_inhrelid;
scan = heap_beginscan(catalogRelation,
SnapshotNow,
1,
&entry);
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
simple_heap_delete(catalogRelation, &tuple->t_self);
found = true;
}
heap_endscan(scan);
heap_close(catalogRelation, RowExclusiveLock);
}
/*
* RelationRemoveIndexes
*/
static void
RelationRemoveIndexes(Relation relation)
{
List *indexoidlist,
*indexoidscan;
indexoidlist = RelationGetIndexList(relation);
foreach(indexoidscan, indexoidlist)
{
Oid indexoid = lfirsti(indexoidscan);
index_drop(indexoid);
}
freeList(indexoidlist);
}
/* --------------------------------
* DeleteRelationTuple
*
* --------------------------------
*/
static void
DeleteRelationTuple(Relation rel)
{
Relation pg_class_desc;
HeapTuple tup;
/*
* open pg_class
*/
pg_class_desc = heap_openr(RelationRelationName, RowExclusiveLock);
tup = SearchSysCacheCopy(RELOID,
ObjectIdGetDatum(rel->rd_id),
0, 0, 0);
if (!HeapTupleIsValid(tup))
elog(ERROR, "Relation \"%s\" does not exist",
RelationGetRelationName(rel));
/*
* delete the relation tuple from pg_class, and finish up.
*/
simple_heap_delete(pg_class_desc, &tup->t_self);
heap_freetuple(tup);
heap_close(pg_class_desc, RowExclusiveLock);
}
/* --------------------------------
* RelationTruncateIndexes - This routine is used to truncate all
* indices associated with the heap relation to zero tuples.
* The routine will truncate and then reconstruct the indices on
* the relation specified by the heapId parameter.
* --------------------------------
*/
static void
RelationTruncateIndexes(Oid heapId)
{
Relation indexRelation;
ScanKeyData entry;
SysScanDesc scan;
HeapTuple indexTuple;
/* Scan pg_index to find indexes on specified heap */
indexRelation = heap_openr(IndexRelationName, AccessShareLock);
ScanKeyEntryInitialize(&entry, 0,
Anum_pg_index_indrelid,
F_OIDEQ,
ObjectIdGetDatum(heapId));
scan = systable_beginscan(indexRelation, IndexIndrelidIndex, true,
SnapshotNow, 1, &entry);
while (HeapTupleIsValid(indexTuple = systable_getnext(scan)))
{
Form_pg_index indexform = (Form_pg_index) GETSTRUCT(indexTuple);
Oid indexId;
IndexInfo *indexInfo;
Relation heapRelation,
currentIndex;
/*
* For each index, fetch info needed for index_build
*/
indexId = indexform->indexrelid;
indexInfo = BuildIndexInfo(indexform);
/*
* We have to re-open the heap rel each time through this loop
* because index_build will close it again. We need grab no lock,
* however, because we assume heap_truncate is holding an
* exclusive lock on the heap rel.
*/
heapRelation = heap_open(heapId, NoLock);
/* Open the index relation */
currentIndex = index_open(indexId);
/* Obtain exclusive lock on it, just to be sure */
LockRelation(currentIndex, AccessExclusiveLock);
/*
* Drop any buffers associated with this index. If they're dirty,
* they're just dropped without bothering to flush to disk.
*/
DropRelationBuffers(currentIndex);
/* Now truncate the actual data and set blocks to zero */
smgrtruncate(DEFAULT_SMGR, currentIndex, 0);
currentIndex->rd_nblocks = 0;
currentIndex->rd_targblock = InvalidBlockNumber;
/* Initialize the index and rebuild */
index_build(heapRelation, currentIndex, indexInfo);
/*
* index_build will close both the heap and index relations (but
* not give up the locks we hold on them).
*/
}
/* Complete the scan and close pg_index */
systable_endscan(scan);
heap_close(indexRelation, AccessShareLock);
}
/* ----------------------------
* heap_truncate
*
* This routine is used to truncate the data from the
* storage manager of any data within the relation handed
* to this routine.
* ----------------------------
*/
void
heap_truncate(Oid rid)
{
Relation rel;
/* Open relation for processing, and grab exclusive access on it. */
rel = heap_open(rid, AccessExclusiveLock);
/*
* TRUNCATE TABLE within a transaction block is dangerous, because if
* the transaction is later rolled back we have no way to undo
* truncation of the relation's physical file. Disallow it except for
* a rel created in the current xact (which would be deleted on abort,
* anyway).
*/
if (IsTransactionBlock() && !rel->rd_myxactonly)
elog(ERROR, "TRUNCATE TABLE cannot run inside a transaction block");
/*
* Release any buffers associated with this relation. If they're
* dirty, they're just dropped without bothering to flush to disk.
*/
DropRelationBuffers(rel);
/* Now truncate the actual data and set blocks to zero */
smgrtruncate(DEFAULT_SMGR, rel, 0);
rel->rd_nblocks = 0;
rel->rd_targblock = InvalidBlockNumber;
/* If this relation has indexes, truncate the indexes too */
RelationTruncateIndexes(rid);
/*
* Close the relation, but keep exclusive lock on it until commit.
*/
heap_close(rel, NoLock);
}
/* --------------------------------
* DeleteAttributeTuples
*
* --------------------------------
*/
static void
DeleteAttributeTuples(Relation rel)
{
Relation pg_attribute_desc;
HeapTuple tup;
int2 attnum;
/*
* open pg_attribute
*/
pg_attribute_desc = heap_openr(AttributeRelationName, RowExclusiveLock);
for (attnum = FirstLowInvalidHeapAttributeNumber + 1;
attnum <= rel->rd_att->natts;
attnum++)
{
tup = SearchSysCacheCopy(ATTNUM,
ObjectIdGetDatum(RelationGetRelid(rel)),
Int16GetDatum(attnum),
0, 0);
if (HeapTupleIsValid(tup))
{
simple_heap_delete(pg_attribute_desc, &tup->t_self);
heap_freetuple(tup);
}
}
heap_close(pg_attribute_desc, RowExclusiveLock);
}
/* --------------------------------
* DeleteTypeTuple
*
* If the user attempts to destroy a relation and there
* exists attributes in other relations of type
* "relation we are deleting", then we have to do something
* special. presently we disallow the destroy.
* --------------------------------
*/
static void
DeleteTypeTuple(Relation rel)
{
Relation pg_type_desc;
HeapScanDesc pg_type_scan;
Relation pg_attribute_desc;
HeapScanDesc pg_attribute_scan;
ScanKeyData key;
ScanKeyData attkey;
HeapTuple tup;
HeapTuple atttup;
Oid typoid;
/*
* open pg_type
*/
pg_type_desc = heap_openr(TypeRelationName, RowExclusiveLock);
/*
* create a scan key to locate the type tuple corresponding to this
* relation.
*/
ScanKeyEntryInitialize(&key, 0,
Anum_pg_type_typrelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
pg_type_scan = heap_beginscan(pg_type_desc,
SnapshotNow,
1,
&key);
/*
* use heap_getnext() to fetch the pg_type tuple. If this tuple is
* not valid then something's wrong.
*/
tup = heap_getnext(pg_type_scan, ForwardScanDirection);
if (!HeapTupleIsValid(tup))
{
heap_endscan(pg_type_scan);
heap_close(pg_type_desc, RowExclusiveLock);
elog(ERROR, "DeleteTypeTuple: type \"%s\" does not exist",
RelationGetRelationName(rel));
}
/*
* now scan pg_attribute. if any other relations have attributes of
* the type of the relation we are deleteing then we have to disallow
* the deletion. should talk to stonebraker about this. -cim 6/19/90
*/
typoid = tup->t_data->t_oid;
pg_attribute_desc = heap_openr(AttributeRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&attkey,
0,
Anum_pg_attribute_atttypid,
F_OIDEQ,
ObjectIdGetDatum(typoid));
pg_attribute_scan = heap_beginscan(pg_attribute_desc,
SnapshotNow,
1,
&attkey);
/*
* try and get a pg_attribute tuple. if we succeed it means we can't
* delete the relation because something depends on the schema.
*/
atttup = heap_getnext(pg_attribute_scan, ForwardScanDirection);
if (HeapTupleIsValid(atttup))
{
Oid relid = ((Form_pg_attribute) GETSTRUCT(atttup))->attrelid;
heap_endscan(pg_attribute_scan);
heap_close(pg_attribute_desc, RowExclusiveLock);
heap_endscan(pg_type_scan);
heap_close(pg_type_desc, RowExclusiveLock);
elog(ERROR, "DeleteTypeTuple: column of type %s exists in relation %u",
RelationGetRelationName(rel), relid);
}
heap_endscan(pg_attribute_scan);
heap_close(pg_attribute_desc, RowExclusiveLock);
/*
* Ok, it's safe so we delete the relation tuple from pg_type and
* finish up.
*/
simple_heap_delete(pg_type_desc, &tup->t_self);
heap_endscan(pg_type_scan);
heap_close(pg_type_desc, RowExclusiveLock);
}
/* ----------------------------------------------------------------
* heap_drop_with_catalog - removes all record of named relation from catalogs
*
* 1) open relation, check for existence, etc.
* 2) remove inheritance information
* 3) remove indexes
* 4) remove pg_class tuple
* 5) remove pg_attribute tuples and related descriptions
* 6) remove pg_description tuples
* 7) remove pg_type tuples
* 8) RemoveConstraints ()
* 9) unlink relation
*
* old comments
* Except for vital relations, removes relation from
* relation catalog, and related attributes from
* attribute catalog (needed?). (Anything else?)
*
* get proper relation from relation catalog (if not arg)
* scan attribute catalog deleting attributes of reldesc
* (necessary?)
* delete relation from relation catalog
* (How are the tuples of the relation discarded?)
*
* XXX Must fix to work with indexes.
* There may be a better order for doing things.
* Problems with destroying a deleted database--cannot create
* a struct reldesc without having an open file descriptor.
* ----------------------------------------------------------------
*/
void
heap_drop_with_catalog(Oid rid,
bool allow_system_table_mods)
{
Relation rel;
Oid toasttableOid;
int i;
/*
* Open and lock the relation.
*/
rel = heap_open(rid, AccessExclusiveLock);
toasttableOid = rel->rd_rel->reltoastrelid;
/*
* prevent deletion of system relations
*/
if (!allow_system_table_mods &&
IsSystemRelation(rel))
elog(ERROR, "System relation \"%s\" may not be dropped",
RelationGetRelationName(rel));
/*
* Release all buffers that belong to this relation, after writing any
* that are dirty
*/
i = FlushRelationBuffers(rel, (BlockNumber) 0);
if (i < 0)
elog(ERROR, "heap_drop_with_catalog: FlushRelationBuffers returned %d",
i);
/*
* remove rules if necessary
*/
if (rel->rd_rules != NULL)
RelationRemoveRules(rid);
/* triggers */
RelationRemoveTriggers(rel);
/*
* remove inheritance information
*/
RelationRemoveInheritance(rel);
/*
* remove indexes if necessary
*/
RelationRemoveIndexes(rel);
/*
* delete attribute tuples
*/
DeleteAttributeTuples(rel);
/*
* delete comments, statistics, and constraints
*/
DeleteComments(rid, RelOid_pg_class);
RemoveStatistics(rel);
RemoveConstraints(rel);
/*
* delete type tuple
*/
DeleteTypeTuple(rel);
/*
* delete relation tuple
*/
DeleteRelationTuple(rel);
/*
* unlink the relation's physical file and finish up.
*/
if (rel->rd_rel->relkind != RELKIND_VIEW)
smgrunlink(DEFAULT_SMGR, rel);
/*
* Close relcache entry, but *keep* AccessExclusiveLock on the
* relation until transaction commit. This ensures no one else will
* try to do something with the doomed relation.
*/
heap_close(rel, NoLock);
/*
* flush the relation from the relcache
*/
RelationForgetRelation(rid);
/* If it has a toast table, recurse to get rid of that too */
if (OidIsValid(toasttableOid))
heap_drop_with_catalog(toasttableOid, true);
}
/*
* Store a default expression for column attnum of relation rel.
* The expression must be presented as a nodeToString() string.
*/
static void
StoreAttrDefault(Relation rel, AttrNumber attnum, char *adbin)
{
Node *expr;
char *adsrc;
Relation adrel;
Relation idescs[Num_pg_attrdef_indices];
HeapTuple tuple;
Datum values[4];
static char nulls[4] = {' ', ' ', ' ', ' '};
Relation attrrel;
Relation attridescs[Num_pg_attr_indices];
HeapTuple atttup;
Form_pg_attribute attStruct;
/*
* Need to construct source equivalent of given node-string.
*/
expr = stringToNode(adbin);
/*
* deparse it
*/
adsrc = deparse_expression(expr,
deparse_context_for(RelationGetRelationName(rel),
RelationGetRelid(rel)),
false);
values[Anum_pg_attrdef_adrelid - 1] = RelationGetRelid(rel);
values[Anum_pg_attrdef_adnum - 1] = attnum;
values[Anum_pg_attrdef_adbin - 1] = DirectFunctionCall1(textin,
CStringGetDatum(adbin));
values[Anum_pg_attrdef_adsrc - 1] = DirectFunctionCall1(textin,
CStringGetDatum(adsrc));
adrel = heap_openr(AttrDefaultRelationName, RowExclusiveLock);
tuple = heap_formtuple(adrel->rd_att, values, nulls);
simple_heap_insert(adrel, tuple);
CatalogOpenIndices(Num_pg_attrdef_indices, Name_pg_attrdef_indices,
idescs);
CatalogIndexInsert(idescs, Num_pg_attrdef_indices, adrel, tuple);
CatalogCloseIndices(Num_pg_attrdef_indices, idescs);
heap_close(adrel, RowExclusiveLock);
pfree(DatumGetPointer(values[Anum_pg_attrdef_adbin - 1]));
pfree(DatumGetPointer(values[Anum_pg_attrdef_adsrc - 1]));
heap_freetuple(tuple);
pfree(adsrc);
/*
* Update the pg_attribute entry for the column to show that a default
* exists.
*/
attrrel = heap_openr(AttributeRelationName, RowExclusiveLock);
atttup = SearchSysCacheCopy(ATTNUM,
ObjectIdGetDatum(RelationGetRelid(rel)),
Int16GetDatum(attnum),
0, 0);
if (!HeapTupleIsValid(atttup))
elog(ERROR, "cache lookup of attribute %d in relation %u failed",
attnum, RelationGetRelid(rel));
attStruct = (Form_pg_attribute) GETSTRUCT(atttup);
if (!attStruct->atthasdef)
{
attStruct->atthasdef = true;
simple_heap_update(attrrel, &atttup->t_self, atttup);
/* keep catalog indices current */
CatalogOpenIndices(Num_pg_attr_indices, Name_pg_attr_indices,
attridescs);
CatalogIndexInsert(attridescs, Num_pg_attr_indices, attrrel, atttup);
CatalogCloseIndices(Num_pg_attr_indices, attridescs);
}
heap_close(attrrel, RowExclusiveLock);
heap_freetuple(atttup);
}
/*
* Store a constraint expression for the given relation.
* The expression must be presented as a nodeToString() string.
*
* Caller is responsible for updating the count of constraints
* in the pg_class entry for the relation.
*/
static void
StoreRelCheck(Relation rel, char *ccname, char *ccbin)
{
Node *expr;
char *ccsrc;
Relation rcrel;
Relation idescs[Num_pg_relcheck_indices];
HeapTuple tuple;
Datum values[4];
static char nulls[4] = {' ', ' ', ' ', ' '};
/*
* Convert condition to a normal boolean expression tree.
*/
expr = stringToNode(ccbin);
expr = (Node *) make_ands_explicit((List *) expr);
/*
* deparse it
*/
ccsrc = deparse_expression(expr,
deparse_context_for(RelationGetRelationName(rel),
RelationGetRelid(rel)),
false);
values[Anum_pg_relcheck_rcrelid - 1] = RelationGetRelid(rel);
values[Anum_pg_relcheck_rcname - 1] = DirectFunctionCall1(namein,
CStringGetDatum(ccname));
values[Anum_pg_relcheck_rcbin - 1] = DirectFunctionCall1(textin,
CStringGetDatum(ccbin));
values[Anum_pg_relcheck_rcsrc - 1] = DirectFunctionCall1(textin,
CStringGetDatum(ccsrc));
rcrel = heap_openr(RelCheckRelationName, RowExclusiveLock);
tuple = heap_formtuple(rcrel->rd_att, values, nulls);
simple_heap_insert(rcrel, tuple);
CatalogOpenIndices(Num_pg_relcheck_indices, Name_pg_relcheck_indices,
idescs);
CatalogIndexInsert(idescs, Num_pg_relcheck_indices, rcrel, tuple);
CatalogCloseIndices(Num_pg_relcheck_indices, idescs);
heap_close(rcrel, RowExclusiveLock);
pfree(DatumGetPointer(values[Anum_pg_relcheck_rcname - 1]));
pfree(DatumGetPointer(values[Anum_pg_relcheck_rcbin - 1]));
pfree(DatumGetPointer(values[Anum_pg_relcheck_rcsrc - 1]));
heap_freetuple(tuple);
pfree(ccsrc);
}
/*
* Store defaults and constraints passed in via the tuple constraint struct.
*
* NOTE: only pre-cooked expressions will be passed this way, which is to
* say expressions inherited from an existing relation. Newly parsed
* expressions can be added later, by direct calls to StoreAttrDefault
* and StoreRelCheck (see AddRelationRawConstraints()).
*/
static void
StoreConstraints(Relation rel, TupleDesc tupdesc)
{
TupleConstr *constr = tupdesc->constr;
int i;
if (!constr)
return; /* nothing to do */
/*
* Deparsing of constraint expressions will fail unless the
* just-created pg_attribute tuples for this relation are made
* visible. So, bump the command counter. CAUTION: this will
* cause a relcache entry rebuild.
*/
CommandCounterIncrement();
for (i = 0; i < constr->num_defval; i++)
StoreAttrDefault(rel, constr->defval[i].adnum,
constr->defval[i].adbin);
for (i = 0; i < constr->num_check; i++)
StoreRelCheck(rel, constr->check[i].ccname,
constr->check[i].ccbin);
if (constr->num_check > 0)
SetRelationNumChecks(rel, constr->num_check);
}
/*
* AddRelationRawConstraints
*
* Add raw (not-yet-transformed) column default expressions and/or constraint
* check expressions to an existing relation. This is defined to do both
* for efficiency in DefineRelation, but of course you can do just one or
* the other by passing empty lists.
*
* rel: relation to be modified
* rawColDefaults: list of RawColumnDefault structures
* rawConstraints: list of Constraint nodes
*
* All entries in rawColDefaults will be processed. Entries in rawConstraints
* will be processed only if they are CONSTR_CHECK type and contain a "raw"
* expression.
*
* NB: caller should have opened rel with AccessExclusiveLock, and should
* hold that lock till end of transaction. Also, we assume the caller has
* done a CommandCounterIncrement if necessary to make the relation's catalog
* tuples visible.
*/
void
AddRelationRawConstraints(Relation rel,
List *rawColDefaults,
List *rawConstraints)
{
char *relname = RelationGetRelationName(rel);
TupleDesc tupleDesc;
TupleConstr *oldconstr;
int numoldchecks;
ConstrCheck *oldchecks;
ParseState *pstate;
RangeTblEntry *rte;
int numchecks;
List *listptr;
Node *expr;
/*
* Get info about existing constraints.
*/
tupleDesc = RelationGetDescr(rel);
oldconstr = tupleDesc->constr;
if (oldconstr)
{
numoldchecks = oldconstr->num_check;
oldchecks = oldconstr->check;
}
else
{
numoldchecks = 0;
oldchecks = NULL;
}
/*
* Create a dummy ParseState and insert the target relation as its
* sole rangetable entry. We need a ParseState for transformExpr.
*/
pstate = make_parsestate(NULL);
rte = addRangeTableEntryForRelation(pstate,
RelationGetRelid(rel),
makeAlias(relname, NIL),
false,
true);
addRTEtoQuery(pstate, rte, true, true);
/*
* Process column default expressions.
*/
foreach(listptr, rawColDefaults)
{
RawColumnDefault *colDef = (RawColumnDefault *) lfirst(listptr);
Form_pg_attribute atp = rel->rd_att->attrs[colDef->attnum - 1];
expr = cookDefault(pstate, colDef->raw_default,
atp->atttypid, atp->atttypmod,
NameStr(atp->attname));
StoreAttrDefault(rel, colDef->attnum, nodeToString(expr));
}
/*
* Process constraint expressions.
*/
numchecks = numoldchecks;
foreach(listptr, rawConstraints)
{
Constraint *cdef = (Constraint *) lfirst(listptr);
char *ccname;
if (cdef->contype != CONSTR_CHECK || cdef->raw_expr == NULL)
continue;
Assert(cdef->cooked_expr == NULL);
/* Check name uniqueness, or generate a new name */
if (cdef->name != NULL)
{
int i;
List *listptr2;
ccname = cdef->name;
/* Check against old constraints */
for (i = 0; i < numoldchecks; i++)
{
if (strcmp(oldchecks[i].ccname, ccname) == 0)
elog(ERROR, "Duplicate CHECK constraint name: '%s'",
ccname);
}
/* Check against other new constraints */
foreach(listptr2, rawConstraints)
{
Constraint *cdef2 = (Constraint *) lfirst(listptr2);
if (cdef2 == cdef ||
cdef2->contype != CONSTR_CHECK ||
cdef2->raw_expr == NULL ||
cdef2->name == NULL)
continue;
if (strcmp(cdef2->name, ccname) == 0)
elog(ERROR, "Duplicate CHECK constraint name: '%s'",
ccname);
}
}
else
{
int i;
int j;
bool success;
List *listptr2;
ccname = (char *) palloc(NAMEDATALEN);
/* Loop until we find a non-conflicting constraint name */
/* What happens if this loops forever? */
j = numchecks + 1;
do
{
success = true;
snprintf(ccname, NAMEDATALEN, "$%d", j);
/* Check against old constraints */
for (i = 0; i < numoldchecks; i++)
{
if (strcmp(oldchecks[i].ccname, ccname) == 0)
{
success = false;
break;
}
}
/*
* Check against other new constraints, if the check
* hasn't already failed
*/
if (success)
{
foreach(listptr2, rawConstraints)
{
Constraint *cdef2 = (Constraint *) lfirst(listptr2);
if (cdef2 == cdef ||
cdef2->contype != CONSTR_CHECK ||
cdef2->raw_expr == NULL ||
cdef2->name == NULL)
continue;
if (strcmp(cdef2->name, ccname) == 0)
{
success = false;
break;
}
}
}
++j;
} while (!success);
}
/*
* Transform raw parsetree to executable expression.
*/
expr = transformExpr(pstate, cdef->raw_expr);
/*
* Make sure it yields a boolean result.
*/
expr = coerce_to_boolean(expr, "CHECK");
/*
* Make sure no outside relations are referred to.
*/
if (length(pstate->p_rtable) != 1)
elog(ERROR, "Only relation \"%s\" can be referenced in CHECK constraint expression",
relname);
/*
* No subplans or aggregates, either...
*/
if (contain_subplans(expr))
elog(ERROR, "cannot use subselect in CHECK constraint expression");
if (contain_agg_clause(expr))
elog(ERROR, "cannot use aggregate function in CHECK constraint expression");
/*
* Might as well try to reduce any constant expressions.
*/
expr = eval_const_expressions(expr);
/*
* Constraints are evaluated with execQual, which expects an
* implicit-AND list, so convert expression to implicit-AND form.
* (We could go so far as to convert to CNF, but that's probably
* overkill...)
*/
expr = (Node *) make_ands_implicit((Expr *) expr);
/*
* Must fix opids in operator clauses.
*/
fix_opids(expr);
/*
* OK, store it.
*/
StoreRelCheck(rel, ccname, nodeToString(expr));
numchecks++;
}
/*
* Update the count of constraints in the relation's pg_class tuple.
* We do this even if there was no change, in order to ensure that an
* SI update message is sent out for the pg_class tuple, which will
* force other backends to rebuild their relcache entries for the rel.
* (This is critical if we added defaults but not constraints.)
*/
SetRelationNumChecks(rel, numchecks);
}
/*
* Update the count of constraints in the relation's pg_class tuple.
*
* Caller had better hold exclusive lock on the relation.
*
* An important side effect is that a SI update message will be sent out for
* the pg_class tuple, which will force other backends to rebuild their
* relcache entries for the rel. Also, this backend will rebuild its
* own relcache entry at the next CommandCounterIncrement.
*/
static void
SetRelationNumChecks(Relation rel, int numchecks)
{
Relation relrel;
HeapTuple reltup;
Form_pg_class relStruct;
Relation relidescs[Num_pg_class_indices];
relrel = heap_openr(RelationRelationName, RowExclusiveLock);
reltup = SearchSysCacheCopy(RELOID,
ObjectIdGetDatum(RelationGetRelid(rel)),
0, 0, 0);
if (!HeapTupleIsValid(reltup))
elog(ERROR, "cache lookup of relation %u failed",
RelationGetRelid(rel));
relStruct = (Form_pg_class) GETSTRUCT(reltup);
if (relStruct->relchecks != numchecks)
{
relStruct->relchecks = numchecks;
simple_heap_update(relrel, &reltup->t_self, reltup);
/* keep catalog indices current */
CatalogOpenIndices(Num_pg_class_indices, Name_pg_class_indices,
relidescs);
CatalogIndexInsert(relidescs, Num_pg_class_indices, relrel, reltup);
CatalogCloseIndices(Num_pg_class_indices, relidescs);
}
else
{
/* Skip the disk update, but force relcache inval anyway */
CacheInvalidateRelcache(RelationGetRelid(rel));
}
heap_freetuple(reltup);
heap_close(relrel, RowExclusiveLock);
}
/*
* Take a raw default and convert it to a cooked format ready for
* storage.
*
* Parse state should be set up to recognize any vars that might appear
* in the expression. (Even though we plan to reject vars, it's more
* user-friendly to give the correct error message than "unknown var".)
*
* If atttypid is not InvalidOid, check that the expression is coercible
* to the specified type. atttypmod is needed in this case, and attname
* is used in the error message if any.
*/
Node *
cookDefault(ParseState *pstate,
Node *raw_default,
Oid atttypid,
int32 atttypmod,
char *attname)
{
Node *expr;
Assert(raw_default != NULL);
/*
* Transform raw parsetree to executable expression.
*/
expr = transformExpr(pstate, raw_default);
/*
* Make sure default expr does not refer to any vars.
*/
if (contain_var_clause(expr))
elog(ERROR, "cannot use column references in DEFAULT clause");
/*
* It can't return a set either.
*/
if (expression_returns_set(expr))
elog(ERROR, "DEFAULT clause must not return a set");
/*
* No subplans or aggregates, either...
*/
if (contain_subplans(expr))
elog(ERROR, "cannot use subselects in DEFAULT clause");
if (contain_agg_clause(expr))
elog(ERROR, "cannot use aggregate functions in DEFAULT clause");
/*
* Check that it will be possible to coerce the expression to the
* column's type. We store the expression without coercion,
* however, to avoid premature coercion in cases like
*
* CREATE TABLE tbl (fld timestamp DEFAULT 'now'::text);
*
* NB: this should match the code in optimizer/prep/preptlist.c that
* will actually do the coercion, to ensure we don't accept an
* unusable default expression.
*/
if (OidIsValid(atttypid))
{
Oid type_id = exprType(expr);
if (type_id != atttypid)
{
if (CoerceTargetExpr(pstate, expr, type_id,
atttypid, atttypmod, false) == NULL)
elog(ERROR, "Column \"%s\" is of type %s"
" but default expression is of type %s"
"\n\tYou will need to rewrite or cast the expression",
attname,
format_type_be(atttypid),
format_type_be(type_id));
}
}
/*
* Might as well try to reduce any constant expressions.
*/
expr = eval_const_expressions(expr);
/*
* Must fix opids, in case any operators remain...
*/
fix_opids(expr);
return(expr);
}
static void
RemoveAttrDefaults(Relation rel)
{
Relation adrel;
HeapScanDesc adscan;
ScanKeyData key;
HeapTuple tup;
adrel = heap_openr(AttrDefaultRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&key, 0, Anum_pg_attrdef_adrelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
adscan = heap_beginscan(adrel, SnapshotNow, 1, &key);
while ((tup = heap_getnext(adscan, ForwardScanDirection)) != NULL)
simple_heap_delete(adrel, &tup->t_self);
heap_endscan(adscan);
heap_close(adrel, RowExclusiveLock);
}
static void
RemoveRelChecks(Relation rel)
{
Relation rcrel;
HeapScanDesc rcscan;
ScanKeyData key;
HeapTuple tup;
rcrel = heap_openr(RelCheckRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&key, 0, Anum_pg_relcheck_rcrelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
rcscan = heap_beginscan(rcrel, SnapshotNow, 1, &key);
while ((tup = heap_getnext(rcscan, ForwardScanDirection)) != NULL)
simple_heap_delete(rcrel, &tup->t_self);
heap_endscan(rcscan);
heap_close(rcrel, RowExclusiveLock);
}
/*
* Removes all CHECK constraints on a relation that match the given name.
* It is the responsibility of the calling function to acquire a lock on
* the relation.
* Returns: The number of CHECK constraints removed.
*/
int
RemoveCheckConstraint(Relation rel, const char *constrName, bool inh)
{
Oid relid;
Relation rcrel;
TupleDesc tupleDesc;
TupleConstr *oldconstr;
int numoldchecks;
int numchecks;
HeapScanDesc rcscan;
ScanKeyData key[2];
HeapTuple rctup;
int rel_deleted = 0;
int all_deleted = 0;
/* Find id of the relation */
relid = RelationGetRelid(rel);
/*
* Process child tables and remove constraints of the same name.
*/
if (inh)
{
List *child,
*children;
/* This routine is actually in the planner */
children = find_all_inheritors(relid);
/*
* find_all_inheritors does the recursive search of the
* inheritance hierarchy, so all we have to do is process all of
* the relids in the list that it returns.
*/
foreach(child, children)
{
Oid childrelid = lfirsti(child);
Relation inhrel;
if (childrelid == relid)
continue;
inhrel = heap_open(childrelid, AccessExclusiveLock);
all_deleted += RemoveCheckConstraint(inhrel, constrName, false);
heap_close(inhrel, NoLock);
}
}
/*
* Get number of existing constraints.
*/
tupleDesc = RelationGetDescr(rel);
oldconstr = tupleDesc->constr;
if (oldconstr)
numoldchecks = oldconstr->num_check;
else
numoldchecks = 0;
/* Grab an appropriate lock on the pg_relcheck relation */
rcrel = heap_openr(RelCheckRelationName, RowExclusiveLock);
/*
* Create two scan keys. We need to match on the oid of the table the
* CHECK is in and also we need to match the name of the CHECK
* constraint.
*/
ScanKeyEntryInitialize(&key[0], 0, Anum_pg_relcheck_rcrelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
ScanKeyEntryInitialize(&key[1], 0, Anum_pg_relcheck_rcname,
F_NAMEEQ,
PointerGetDatum(constrName));
/* Begin scanning the heap */
rcscan = heap_beginscan(rcrel, SnapshotNow, 2, key);
/*
* Scan over the result set, removing any matching entries. Note that
* this has the side-effect of removing ALL CHECK constraints that
* share the specified constraint name.
*/
while ((rctup = heap_getnext(rcscan, ForwardScanDirection)) != NULL)
{
simple_heap_delete(rcrel, &rctup->t_self);
++rel_deleted;
++all_deleted;
}
/* Clean up after the scan */
heap_endscan(rcscan);
heap_close(rcrel, RowExclusiveLock);
if (rel_deleted)
{
/*
* Update the count of constraints in the relation's pg_class tuple.
*/
numchecks = numoldchecks - rel_deleted;
if (numchecks < 0)
elog(ERROR, "check count became negative");
SetRelationNumChecks(rel, numchecks);
}
/* Return the number of tuples deleted, including all children */
return all_deleted;
}
static void
RemoveConstraints(Relation rel)
{
TupleConstr *constr = rel->rd_att->constr;
if (!constr)
return;
if (constr->num_defval > 0)
RemoveAttrDefaults(rel);
if (constr->num_check > 0)
RemoveRelChecks(rel);
}
static void
RemoveStatistics(Relation rel)
{
Relation pgstatistic;
HeapScanDesc scan;
ScanKeyData key;
HeapTuple tuple;
pgstatistic = heap_openr(StatisticRelationName, RowExclusiveLock);
ScanKeyEntryInitialize(&key, 0x0, Anum_pg_statistic_starelid,
F_OIDEQ,
ObjectIdGetDatum(RelationGetRelid(rel)));
scan = heap_beginscan(pgstatistic, SnapshotNow, 1, &key);
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
simple_heap_delete(pgstatistic, &tuple->t_self);
heap_endscan(scan);
heap_close(pgstatistic, RowExclusiveLock);
}
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